SharePoint isn't really designed to support a split geographic installation within a farm. There is no way to overcome the SQL latency issues that develop and its not a supported scenario. Yet, there are a couple of options you can pursue:
Info taken from: http://social.technet.microsoft.com/Forums/en-US/sharepointgeneral/thread/aaf7af12-4f1a-4c28-9f0c-7f87d46ec2b1
The SharePoint 2013 Best Practices page at http://social.technet.microsoft.com/wiki/contents/articles/12438.sharepoint-2013-best-practices.aspx
Margriet Bruggeman edited Revision 2. Comment: add
Margriet Bruggeman edited Revision 1. Comment: add
Margriet Bruggeman edited Original. Comment: add